Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

R. Sinha ¹, B. C. Raymahashay ¹

Affiliations
1 Engineering Geology Group, Department of Civil Engineering, Indian Institute of Technology, Kanpur - 208016, IN

Abstract

The Sambhar lake of central Rajasthan, located between Ajmer and Jaipur, is a hypersaline lake. The present study focuses on the mineralogy of the lacustrine sediments of this region. X-ray diffraction patterns of shaflow auger hole samples show a broad pattern of fluctuation in vertical profiles. It is apparent that rock weathering in the catchment area supplies a flux of clastic minerals like quartz, feldspar and mica during the wet period. This is followed by an evaporite sequence of carbonate-sulfate-chloride in dry climate. Thus, an abundance of calcite indicates the beginning of evaporation, while later stages are characterized by the dominance of thenardite and finally of halite.

Keywords

Sedimentology, Sediment Geochemistry, Clay Minerals, Evaporites, Saline Lake.

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B. C. Raymahashay ¹

Affiliations
1 Indian Institute of Technology, Kanpur, IN

Abstract

Recent field data on hydrothermal ore deposits and experimental data on solution chemistry of minerals and dissolved species have been applied to certain Precambrian ore deposits of India. Parameters of the environment of ore deposition like temperature, fugacity of gases and concentration of dissolved species have been calculated from selected mineral assemblages. Possible lines of future research have been suggested and gaps in the present knowledge pointed out .

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K. H. Vora ¹, B. C. Raymahashay ²

Affiliations
1 Geological Oceanography Division, NIO, Dona Paula, Goa, IN
2 Department of Civil Engineering, Indian Institute of Technology, Kanpur-208016, IN

Abstract

The joint planes of massive limestone at Sahasradhara, Dehra Dun have a thin crust containing jarosite with gypsum blades. This occurrence is different from the usual chemical weathering in a ferruginous environment. An evaluation of the chemistry of local river and groundwater suggests that these minerals form by evaporation in dry seasons.

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A. K. Chaturvedi ¹, B. C. Raymahashay ¹

Affiliations
1 Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, IN

Abstract

Gangetic alluvial soils of Uttar Pradesh typically contain carbonate concretions (kankar) of different morphology at various depths. The concretion mineralogy has been correlated with local groundwater chemistry by calculating mineral solubility products from available thermodynamic data. It is concluded that carbonate minerals are precipitated from supersaturated groundwater in pore space leading to formation of concretions.

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B. C. Raymahashay ¹, P. R. Bhavana ¹, K. S. Rao ¹, V. K. Mehta ¹

Affiliations
1 Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, IN

Abstract

The lateritic soils developed over Precambrian crystalline rocks near Calicut have relatively high Cation Exchange Capacity. At the same time, the soils are highly efficient for phosphate uptake. Both of these properties are traced to the presence of halloysite of intermediate hydration in the soils. Experimental results have been interpreted in terms of the structure of soil minerals.

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B. C. Raymahashay ¹

Affiliations
1 Department of Civil Engineering, Indian Institute of Technology, Kanpur 208 016, IN

Abstract

The structure of montmorillonite provides two exchange sites; one at the surface and the other between the silicate layers. This is confirmed by the dibasic nature of H-montmorillonite. As a consequence, montmorillonite is capable of removing larger amounts of cationic pollutants compared with kaolinite. Anion uptake is relatively feeble and similar for the two clays. A review of recent experiments suggests that clayey soils could act as barriers against dispersion of toxic metals, detergents and dyes.

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